Lubricant



was Mar. '4, 1941 UNITED, STATES.

2,233,426 PATENT OFFICE LUBRICANT John G. McNab, Roselle, N. 1., assignor to Standard 01] Development Company, a corporation of Delaware No Drawing. Application October 14, 1938, Serial No. 234,899

12 Claims.

The present invention relates to improved lubricants and especially to oils for the lubrication of automotive engines, and particularly Diesel engines. The invention will be fully 5, understood from the following description.

During the past several years it has been found desirable to add certain polyvalent metal soaps to lubricants, especially such lubricants as are used for automotive engines of the Diesel type. The function of these soaps is complex but the effect is mainly one of maintaining a clean engine condition. The various soaps have peculiarities in behavior depending on the particular metals and to some degree the acid radicals with which they are combined.' Certain of the soaps are com-' pletely insoluble and others, while soluble, cause gelling of the oil. Still others are capable of giving clean engines, but (10 not appear to be able to reduce engine wear orperhaps even cause excessive engine wear. Thus the various soaps,

, whiletheir functions may in some cases overlap,

are not equivalents in some certain respects.

It has now been found that certain mixed soap compositions are very much superior to compositions containing a single soap. 0f the various soaps to be under consideration here, there appear to be three general groups; the first comprises calcium and magnesium soaps which' appear to be interchangeable, although they maybe used together if desired. The second I type of soap is that of aluminum and the third of C., such'as capric, lauric and the like. Various sults' have been obtained by use of three soaps,

nickelgaluminum and calcium or magnesium.

It has been stated that the type of acids used is important. Any of the fatty acids may be employed but it is preferable to use predominantly saturated fatty acids with melting points below 50 C. The higher melting acids such as st'earic and palmitic are less desirable because their soaps have a tendency to be less soluble than those of acids having melting points below 50 mixed acids may be used such as are obtained from the commercial fats or may be made up synthetically, and it is found that if a substantial portion of unsaturated acids be present, say from aboutjlO to 30%. oil solubility is more readily obtained. Unsaturated acids such as oleic or erucic can also be .used alone. Another type of. acids that maybe employed is that produced by low temperature oxidation of parailin wax with air, preferably using catalysts. Highly refined oils may be oxidized in the same way, for ex-' ample, highly solvent extracted oils or hydrogenated oils, but the most suitable product appears to be the so-called oxidized acids which are obtained from sweater oil. This oil is sweatd from petroleum waxes and is oxidized catalytica'la ly with air at temperatures from about to C. Naphthenic acids such as those obtained from Venezuelan, Colombian, Gulf Coast, and Roumanian crudes may also be used in making the soaps.

' In manufacturing the soaps, the best procedure is to first obtain a soda or potash soap of the particular organic acid or mixture of acids and then prepare the polyvalent metal soap mixture from the soda or potash soap by double decomposition using water soluble salts of the-polyvalentmetals, for example chlorides or nitrates. In some-instances, thev polyvalent soaps may be prepared separately and then mixed together, but it is generally preferable to make a mixture of the polyvalent soaps directly by c-precipitation and this is particularly useful when calcium soaps are employed because they have a tendency to be less'soluble than the other metal soaps and the materials co-precipitation method produces which are freely soluble.

The amount of the soap may'vary somewhat depending on the particular soaps employed and the service in which they are to be used, but the total amount of the polyvalent metal soap varies in general from about t; to 3 of the oil. The various soaps may be used in equal proportions, but good results are obtained over a fairly large range of variation in proportions. It is preferable toprovide that each of the two or more soaps is present in not less than 1% "of the total soap.

Thus if 3% of the total soap is em- "ployed, the mixture may contain from about .3

to 2.7% of the aluminum soap withfrom 2.7 to .3% of calcium, magnesium or nickel soap.

It is found desirable to use soap mixtures which are substantially free from non-saponaceous ingredients such as. free acids, esters. lactones,

lactides, and the like and this may be accom-- plished in various ways, butthe best method is by extracting the soap mixtures with oxygencontaining solvents such 'as alcohols, ketones, and the like in which the polyvalent soaps are relatively insoluble.

In spite of what has been said in the paragraph above, it has been found desirable to addsmall amounts of certain specific acids to the soap mixtures, but'these acids are not of the preferred 1 type used in manufacturing polyvalent soap. The best acid to be added appears of stearic acid bu't similar-high molecular weight to. be a good grade and these compositions are especially desirable for the lubrication of Diesel engines. The oils are preferably well refined having viscosities from 45 to 65 seconds Saybolt at 210 F., and it is preferred that they have pour points of F., or below; whether obtainednaturally or by dewaxing or by the use of pour depressants is not important. The essential ingredients of the present composition are the two or more polyvalent soaps of the types mentioned above and the hydrocarbon oil, but other ingredients may be employed such ,as sludge dispersing agents, oxidation inhibitors, thickening agents, sulfur or phosphorus containing compounds, and the like.

Examples Lubricating oils made from naphthenic lubricating distillate having a viscosity of .about 55 seconds at 210 Fl Sample 1 contained 1% of an aluminum soap of: an oxidized sweater oil acid and .5% of free stearic acid. Sample 2 contained 1% of a calcium soap of the same oxidized sweater acids and .5% of naphthenic acid which was used to solubilize the calcium sweater oil acids soap. Sample 3 contained 175% of a mixture of aluminum and calciumsweater oil acids soaps in equal proportions. This mixture was prepared by co-precipitation of the said soaps by addition of aluminum and calcium chlorides tothe soda soap of the oxidized sweater oil acids. The blend also contained .5% added free stearic acid. 5

Each of the three samples described "above was subjected to a test over long periods in a Caterpillar single cylinder. Diesel engine under comparable rlmning conditions. After each test the pistons were taken down and examined carefully and a demerit rating was assigned to each part depending on its condition, for example, to the rings, slits, and grooves, filter. pistonskirt, and liners. -In considering these demerit numbers, it should be borne in mind that the lower numbers indicate superior condition. The demerit numbers were then weighted to obtain an overall demerit for'the piston as a whole. The amoimt of oil used was measured as well as the wear on the liner. All of these data are assembled in the following table:

The overall demerit rating is much better and only in one comparison is it inferior to either of the other samples. This is in respect to the sharpness of the ring edge, but it is clear. that thisis not of very great importance and is much overshadowed by the improved condition of the slits, grooves, etc., the decrease in the varnish and the improvedv filter condition.

4 This invention is not to be limited by any specific examples which have been presented herein solely for the purpose ofillustration, but

only by the following claims. in which it is desired to claim all vention.

I claim:

1. An improved crankcase lubricating composinovelty inherent in the intion comprising a mineral lubricating oil and a small amounts of polyvalent metal soaps selected from at least two of thevgroups of aluminum, nickel, and the alkaline earth soaps the total amount of soaps present being from {a to 3'/ z% of the oil, and the amount of soap from anyone of the three groups being at least 10% of the total amount of soap present.

2. Lubricant according to claim 1, in which 3%% of mixed soaps, the said soaps being Prepared from soda soaps of organic acids by 00-.

precipitation with water soluble salts of aluminum and a metal selected from the group consisting of calcium and magnesium the amount of each soap in the lubricant being at least 10% of the total amount of soaps present.

' 4. Lubricating oil according to claim 3 in which the soap is prepared from oxidized sweaterv oil ac d.

5. An improved lubricant for Diesel engines comprising a mineral lubricating oil and 1b to ti /2% of mixed soaps, the said soaps being prepared from soda soaps of organic acids by coprecipitation withwater soluble salts of nickel and a metal selected from the group consisting of calcium and magnesium the amount of each soap in the-lubricant'being'at least 10% of the total amount of soap present.

6. Lubricating oil according to claim 5 in which 7. Lubricant according to claim 1, in which the total-soap content is from \s to 3% and is pre- I pared by co-precipitation of the two soaps by re- 1 Caterpillar singlecylinder engine tests I Hts Lin Oilcons. Sample Eng. Bun 3.11.1.

No. No. No. Hm Ovanll Ring mmmmm cm Skirt Varnish-'01! hrs.l I 3 and on umgallon sue. Grooves sons Max Av.

1 c4 500 1.35 0.11 0.0 3.1 1.72 4.6 o.92 1.0 2 3200 0.0046 0.0015 I 2.00 0.07 0.5 4.5 2.52 5.0 L92 -0.8 5 35H) 0.!!! 0.0)16 2. 0-1 17 D 2.25 0.17 3.0 4.2 3J3 -4.8 3.33 4 4 348) 0.0028 0.)12 3 s 500 1.13 0.25 0.0 2.3 I. 4.. 0.07 '02.: L0 7770 0.0056 0.)16 1000 1.48 1.! 0.25 3.6 3.01 4.3 0.61 0.) 2.0 3565 0.11722 0.0009

Cleanlinessoirl'ngslitagroovealandaandsldm.

Fromtheabove dataltisclearthattheoil containing both the calcium .and theaIuminum with-.water soluble salts of thepolyvalent metals." soap, Sample 3, is much superior to either of; the blends in whichthe single'soaps are 1. comprising a mineral lubricating oilandi to 7'5 action of alkali metal soaps of naphthen ic acids 8. An improved lubricant i81- Diesel engines 3/z% of mixed soaps, the said soaps being prepared from soda soaps by co-precipitation with water soluble salts of nickel, aluminum, and a metal selected from the group consisting of calcium andmagnesium the amount of each soap in the lubricant being at least 10% of the total amount of soap present. I

9. Lubricant according to claim 1, in which the mineral lubricating oil present, is a refined mineral oil having a viscosity of to 65 seconds Saybolt at 210 F. anda pour point at least as low as 0 F.

, '10. Lubricant according to claim 1 in which the soap-iorming acidic material has been substantially Ireed irom non-saponaceous ingredients such as free acids, esters, lactones, lactides and the like. a

11. An improved crankcase lubricant for Diesel engines comprising a major proportion of naphthenic lubricating oil distillates having a viscosity of about 45 to 65 seconds Saybolt at 210 E, into which has been incorporated from 6 to 3 /2% of mixed soaps of polyvalent metals selected from at least two of the groups aluminum,

nickel and alkaline earth soaps, said soaps being prepared fromsaturated fatty acids having a melting point below about C. the amount 

